Method for manufacturing light-emitting device

ABSTRACT

An object of one embodiment of the present invention is to provide a more convenient highly reliable light-emitting device which can be used for a variety of applications. Another object of one embodiment of the present invention is to manufacture, without complicating the process, a highly reliable light-emitting device having a shape suitable for its intended purpose. In a manufacturing process of a light-emitting device, a light-emitting panel is manufactured which is at least partly curved by processing the shape to be molded after the manufacture of an electrode layer and/or an element layer, and a protective film covering a surface of the light-emitting panel which is at least partly curved is formed, so that a light-emitting device using the light-emitting panel has a more useful function and higher reliability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting device and amanufacturing method thereof.

2. Description of the Related Art

In recent years, light-emitting devices have been used in a variety ofplaces for a variety of applications and therefore have been required tohave various characteristics and shapes. Accordingly, light-emittingdevices serving their intended purposes have been actively developed.

For example, as a light-emitting device which is provided for anamusement machine, a display whose display surface is curved so thatplayers can experience stereoscopic effect has been reported (e.g., seePatent Document 1).

As the light-emitting device, a light-emitting device having alight-emitting element (hereinafter also referred to as an EL element)exhibiting electroluminescence (hereinafter also referred to as EL),which is lightweight and can realize high contrast and wide viewingangle, is used.

REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No.    H7-114347

SUMMARY OF THE INVENTION

However, the EL element easily deteriorates due to a contaminant such asmoisture which enters from outside and this deterioration is one of thefactors that reduce reliability of a light-emitting device.

Thus, an object of one embodiment of the present invention is to providea more convenient highly reliable light-emitting device which can beused for a variety of applications. Another object of one embodiment ofthe present invention is to manufacture, without complicating theprocess, a highly reliable light-emitting device having a shape suitablefor its intended purpose.

In a manufacturing process of a light-emitting device, a light-emittingpanel is manufactured which is at least partly curved by processing theshape to be molded after the manufacture of an electrode layer and/or anelement layer, and a protective film covering a surface of thelight-emitting panel which is at least partly curved is formed, so thata light-emitting device using the light-emitting panel has a more usefulfunction and higher reliability.

The shape of the light-emitting device can be freely determined byselecting the shape of a mold used for shaping the light-emittingdevice. Accordingly, it is possible to manufacture various kinds oflight-emitting devices capable of being used in a variety of places fora variety of applications, which allows a highly convenientlight-emitting device to be provided.

In addition, in the case where the light-emitting panel in which theelectrode layer and/or the element layer has been manufactured and thenthe protective film has been formed is processed into a shape having acurved portion, shape defects such as damage of the protective film dueto the shape processing occur. In contrast, it is possible to preventoccurrence of shape defects such as damage of the protective film due tothe shape processing of the light-emitting panel in such a manner thatthe protective film is formed on the light-emitting panel that has beenprocessed into the shape having the curved portion. As a result, theprotective film which is a dense film blocks moisture or otherimpurities from the outside, and contamination of a light-emittingdevice can be efficiently prevented.

According to one embodiment of the invention disclosed in thisspecification, a light-emitting panel having a light-emitting elementbetween a pair of flexible sealing members is formed, the light-emittingpanel is processed into a shape at least partly curved, and a protectivefilm is formed to cover the light-emitting panel which is processed intothe shape at least partly curved.

According to another embodiment of the invention disclosed in thisspecification, a light-emitting panel having a light-emitting elementbetween a pair of flexible sealing members is formed, the light-emittingpanel is processed into a shape at least partly curved and held by asupporting member, and a protective film is formed to cover thelight-emitting panel which is processed into the shape at least partlycurved.

According to another embodiment of the invention disclosed in thisspecification, a first sealing member which is at least partly curvedand provided with a first electrode layer is formed; an EL layer isformed over the first electrode layer; a second electrode layer isformed over the EL layer; a second sealing member is disposed so thatthe first electrode layer, the EL layer, and the second electrode layerare sealed between the first sealing member and the second sealingmember to form a light-emitting panel which is at least partly curved;and a protective film is formed to cover the light-emitting panel whichis at least partly curved.

According to another embodiment of the invention disclosed in thisspecification, a first sealing member provided with a first electrodelayer is provided in contact with an inner surface of a supportingmember which is at least partly curved; an EL layer is formed over thefirst electrode layer; a second electrode layer is formed over the ELlayer; a second sealing member is disposed so that the first electrodelayer, the EL layer, and the second electrode layer are sealed betweenthe first sealing member and the second sealing member to form alight-emitting panel which is at least partly curved; and a protectivefilm is formed to cover the light-emitting panel which is at leastpartly curved.

In the above-described structures, another protective film may be formedbetween the sealing member which seals the light-emitting element (e.g.,a flexible substrate) and the light-emitting element.

The light-emitting device may include a sensor portion. For example, atouch sensor (a touch panel) can be provided in a supporting member onthe viewer side.

Note that the ordinal numbers such as “first” and “second” are used forconvenience and do not denote the order of steps and the stacking orderof layers. In addition, the ordinal numbers in this specification do notdenote particular names which specify the present invention.

Note that a semiconductor device in this specification refers to all thedevices that can operate by using semiconductor characteristics, and anelectro-optical device, a semiconductor circuit, and an electronicappliance are all included in the semiconductor device.

The shape of the light-emitting device can be freely determined byselecting the shape of a mold used for shaping the light-emittingdevice. Accordingly, it is possible to manufacture various kinds oflight-emitting devices capable of being used in a variety of places fora variety of applications, which allows a highly convenientlight-emitting device to be provided.

It is possible to prevent occurrence of shape defects such as damage ofthe protective film due to the shape processing of the light-emittingpanel because the protective film is formed on the light-emitting panelthat has been processed into the shape having the curved portion. As aresult, the protective film which is a dense film blocks moisture orother impurities from the outside, and contamination of a light-emittingdevice can be efficiently prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1F are views illustrating a method for manufacturing alight-emitting device;

FIGS. 2A to 2E are views illustrating a method for manufacturing alight-emitting device;

FIGS. 3A to 3C are views illustrating a light-emitting device;

FIGS. 4A to 4C are views illustrating a light-emitting device;

FIGS. 5A and 5B are views illustrating a light-emitting device;

FIGS. 6A and 6B are views each illustrating a light-emitting module;

FIGS. 7A to 7F are views illustrating a method for manufacturing alight-emitting device;

FIG. 8 is a view illustrating a light-emitting module;

FIGS. 9A to 9D are views each illustrating a semiconductor element thatcan be applied to a light-emitting device;

FIGS. 10A to 10D are views illustrating an example of a cellular phoneto which a light-emitting device is applied;

FIG. 11 is a view illustrating an example of a cellular phone to which alight-emitting device is applied;

FIGS. 12A and 12B are views each illustrating a light-emitting elementwhich can be applied to a light-emitting device;

FIGS. 13A to 13E are views illustrating a method for manufacturing alight-emitting device;

FIGS. 14A to 14C are views each illustrating a light-emitting module;and

FIGS. 15A and 15B are views each illustrating a light-emitting device.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described in detail withreference to the accompanying drawings. However, the present inventionis not limited to the following description, and various changes for themodes and details thereof will be apparent to those skilled in the artunless such changes depart from the spirit and the scope of theinvention. Therefore, the present invention should not be interpreted asbeing limited to the description of the embodiments below. In thestructures described below, the same portions or portions having similarfunctions are denoted by the same reference numerals in differentdrawings, and description thereof will not be repeated.

Embodiment 1

A light-emitting device will be described with reference to FIGS. 1A to1F and FIGS. 5A and 5B.

FIGS. 1A to 1F and FIGS. 5A and 5B are cross-sectional viewsillustrating a light-emitting device and a method for manufacturing alight-emitting device.

The light-emitting device includes a light-emitting element having atleast a first electrode layer, an EL layer, and a second electrodelayer; and a pair of sealing members which seals the light-emittingelement therebetween. The light-emitting device may also be providedwith a semiconductor element, preferably a thin film transistor. In thecase of an active matrix light-emitting device, a driving thin filmtransistor is provided in each pixel.

Although an active matrix light-emitting device is shown as an examplein this embodiment, this embodiment can also be applied to a passivematrix light-emitting device.

In this embodiment, a light-emitting panel is manufactured which is atleast partly curved by processing the shape to be molded after themanufacture of an electrode layer of a light-emitting element and/or anelement layer including a semiconductor element, and a protective filmcovering a surface of the light-emitting panel which is at least partlycurved is formed, so that a light-emitting device using thelight-emitting panel has a more useful function and higher reliability.

An element layer 101 is formed over a manufacturing substrate 100 (seeFIG. 1A). The element layer 101 includes a thin film transistor. Next,the element layer 101 is transferred to a supporting substrate 102 (seeFIG. 1B).

The manufacturing substrate 100 may be selected as appropriate in amanner that depends on the manufacturing process of the element layer101. For example, a glass substrate, a quartz substrate, a sapphiresubstrate, a ceramic substrate, a metal substrate having an insulatinglayer on its surface, or the like can be used as the manufacturingsubstrate 100. A plastic substrate having heat resistance which canwithstand the processing temperature may also be used.

The element layer 101 is transferred from the supporting substrate 102to a first sealing member 110 (see FIG. 1C).

A light-emitting element 125 electrically connected to the element layer101 is formed, and a second sealing member 120 covering the elementlayer 101 and the light-emitting element 125 is formed. Accordingly, aflexible light-emitting panel 155 a is manufactured in which the elementlayer 101 and the light-emitting element 125 which are sealed betweenthe first sealing member 110 and the second sealing member 120 areincluded (see FIG. 1D).

The flexible light-emitting panel 155 a is at least sealed between apair of sealing members, which may be a substrate or a film as long asit is flexible. The light-emitting panel 155 a is an example in whichthe first sealing member 110 having a shape of a plate and the secondsealing member 120 having a shape of a resin layer are used. As asealing means, a plurality of sealing members which attach the sealingmembers to each other or sealing members having different shapes may beused. FIGS. 5A and 5B illustrate other examples of a flexiblelight-emitting panel.

FIG. 5A illustrates an example, which is a flexible light-emitting panel155 b in which a third sealing member 128 having a shape of a plate isfurther provided over the second sealing member 120 having a shape of aresin layer. In addition, FIG. 5B illustrates another example, which isa flexible light-emitting panel 155 c in which the first sealing member110 and the third sealing member 128 are further attached to each otherwith a sealant 124.

An ultraviolet curable resin or a thermosetting resin can be used forthe sealing member having a shape of a resin layer like the secondsealing member 120. For example, polyvinyl chloride (PVC), acrylic,polyimide, an epoxy resin, a silicone resin, polyvinyl butyral (PVB), orethylene vinyl acetate (EVA) can be used. When a hygroscopic substancesuch as a desiccating agent is used as the sealing member, or ahygroscopic substance is added to the sealing member, higher moistureabsorbing effect can be achieved and deterioration of elements can beprevented.

As the sealant 124, it is typically preferable to use a visible lightcurable resin, an ultraviolet light curable resin, or a thermosettingresin. Typically, an acrylic resin, an epoxy resin, an amine resin, orthe like can be used. The sealant 124 may include a photopolymerizationinitiator (typically, an ultraviolet light polymerization initiator), athermosetting agent, a filler, or a coupling agent.

The attachment step of the first sealing member 110 and the thirdsealing member 128 with the sealant 124 may be performed under reducedpressure.

As the supporting substrate 102, the first sealing member 110, and thethird sealing member 128, a film or substrate having flexibility (aflexible substrate) is used. However, the first sealing member 110, thesecond sealing member 120, and the third sealing member 128 that havebeen shaped and fixed do not need to have flexibility. The supportingsubstrate 102, the first sealing member 110, the second sealing member120, and the third sealing member 128 can be formed using an aramidresin, a polyethylene naphthalate (PEN) resin, a polyether sulfone (PES)resin, a polyphenylene sulfide (PPS) resin, a polyimide (PI) resin, orthe like. Alternatively, a prepreg that is a structure body in which afiber is impregnated with an organic resin may be used. In the casewhere there is no necessity of a light-transmitting property, a metalfilm such as stainless steel may also be used.

A protective film such as an inorganic insulating film may be providedfor the sealing members. For example, when the protective film isprovided on the element layer 101 side in the first sealing member 110,the protective film can block a contaminant from entering the elementlayer 101 from outside or the first sealing member 110. In addition,when the protective film is provided outside (the side opposite to theside where the element layer 101 is formed) in the first sealing member110, the protective film can block a contaminant from entering the firstsealing member 110 itself and thus deterioration can be prevented.

A hygroscopic substance serving as a desiccating agent may be providedfor the sealing members. For example, a film of a hygroscopic substancesuch as barium oxide may be formed on the sealing members with asputtering method.

Note that in this specification, the attachment between the sealingmember or a supporting member and the element layer or thelight-emitting element can be performed using a bonding layer. Theelement layer is attached to the supporting substrate in thetransferring step preferably using an adhesive which can be separatedlater. For example, the supporting substrate is temporary bonded to theelement layer and the like, using a water-soluble adhesive, so that thesupporting substrate may be separated from the element layer by washingwith water.

The shape of the flexible light-emitting panel 155 a is processed to bebent, whereby a light-emitting panel 150 having a curved portion ismanufactured (see FIG. 1E). The shape processing may be performed usinga support which serves as a mold of the light-emitting panel.

A protective film 126 is formed to cover the light-emitting panel 150(see FIG. 1F). The shape of the light-emitting panel 150 having thecurved portion (see FIG. 1E) can be made to correspond to the shape ofthe protective film owing to thinness of the protective film 126.

Since the protective film 126 is formed on the light-emitting panel 150that has been processed into the shape having the curved portion, it ispossible to prevent occurrence of shape defects such as damage of theprotective film 126 due to the shape processing of the light-emittingpanel 150. As a result, the protective film 126 which is a dense filmblocks moisture or other impurities from the outside, and thecontamination of a light-emitting device having the light-emitting panel150 can be efficiently prevented.

The protective film 126 can be formed with the following method whichdepends on a material thereof: a sputtering method, a CVD method, anevaporation method, a SOG method, spin coating, dipping, spray coating,a droplet discharging method (e.g., an ink-jet method, screen printing,or offset printing), doctor knife, roll coater, curtain coater, knifecoater, or the like. Examples of the inorganic material used for theprotective film 126 include silicon oxide, silicon nitride, siliconoxynitride, aluminum oxide, aluminum nitride, and aluminum oxynitride.Preferably, the protective film 126 may be formed with a sputteringmethod, using silicon nitride.

In addition, in part of a region other than a display portion, wherelight from the light-emitting element is not extracted, a metal film orthe like which has a non-light-transmitting property may be used for theprotective film 126.

The protective film 126 may be formed to have a single layer structureor a stacked structure. For example, the light-emitting panel 150 may becovered with an organic resin layer and further an inorganic film may bestacked thereover to cover the organic resin layer. There is noparticular limitation on the material and the formation method of theprotective film as long as it is a dense film which has an effect ofpreventing entry of contaminant impurities such as an organic substance,a metal, or moisture floating in air.

It is not always necessary that the protective film be formed to coverthe entire surface of the light-emitting panel as long as it is formedto cover at least a region including a curved portion which is used as adisplay region. FIG. 15A illustrates an example of the curvedlight-emitting panel 150 in which a protective film 130 is formed on thesecond sealing member 120 side.

In addition, the step of forming the protective film may be performedonce or plural times. FIG. 15B illustrates an example of the curvedlight-emitting panel 150 in which a protective film 131 a is formed onthe second sealing member 120 side and a protective film 131 b is formedon the first sealing member 110 side. In the case where protective filmsare formed through a plurality of steps, the protective films may bepartly stacked like the protective films 131 a and 131 b.

When a protective film is formed to cover an end portion of thelight-emitting panel, which is not covered with a sealing member,deterioration of a light-emitting element is effectively prevented.

Although not illustrated in this embodiment, a color filter (a coloringlayer); a black matrix (a light-shielding layer); an optical member (anoptical substrate) such as a polarizing member, a retardation member, oran anti-reflection member; and the like are provided as appropriate. Forexample, circular polarization may be obtained using a polarizingsubstrate and a retardation substrate.

When the flexible light-emitting panel 155 a is shaped into thelight-emitting panel 150, fixing treatment such as heat treatment orlight irradiation treatment may be performed so that the obtained shapeis fixed. Alternatively, the flexible light-emitting panel 155 a may beshaped into the light-emitting panel 150 by heat treatment and cooledwhile the obtained shape is kept as it is so that the shape of thelight-emitting panel 150 is fixed.

The element layer 101 may be directly formed on the sealing member 110.For example, an electrode layer of a light-emitting element may bedirectly formed on the supporting substrate 102 or the first sealingmember 110 with a printing method or the like.

There is no particular limitation on the method for transferring theelement layer 101 from the manufacturing substrate 100 to anothersubstrate as shown in this embodiment, and a variety of methods can beused. For example, a separation layer may be formed between themanufacturing substrate and the element layer.

With a sputtering method, a plasma CVD method, a coating method, aprinting method, or the like, the separation layer is formed as a singlelayer or staked layers, using an element selected from tungsten (W),molybdenum (Mo), titanium (Ti), tantalum (Ta), niobium (Nb), nickel(Ni), cobalt (Co), zirconium (Zr), zinc (Zn), ruthenium (Ru), rhodium(Rh), palladium (Pd), osmium (Os), iridium (Ir), or silicon (Si); or analloy material or a compound material containing any of these elementsas its main component. A layer containing silicon may have anycrystalline structure: an amorphous structure; a microcrystallinestructure; or a polycrystalline structure. Note that the coating methodincludes here a spin coating method, a droplet discharging method, and adispensing method.

In the case where the separation layer has a single layer structure, itis preferable to form a tungsten layer, a molybdenum layer, or a layercontaining a mixture of tungsten and molybdenum. Alternatively, theseparation layer may be a layer containing an oxide or oxynitride oftungsten, a layer containing an oxide or oxynitride of molybdenum, or alayer containing an oxide or oxynitride of a mixture of tungsten andmolybdenum. Note that the mixture of tungsten and molybdenum correspondsto an alloy of tungsten and molybdenum, for example.

In the case where the separation layer has a stacked structure, it ispreferable that a tungsten layer, a molybdenum layer, or a layercontaining a mixture of tungsten and molybdenum be formed as a firstlayer, and a layer containing an oxide, nitride, oxynitride, or nitrideoxide of tungsten, molybdenum, or a mixture of tungsten and molybdenumis formed as a second layer.

In the case where the separation layer has a stacked structure of alayer containing tungsten and a layer containing an oxide of tungsten,it may be formed in such a manner that a layer containing tungsten isformed and an insulating layer containing an oxide is formed thereover,so that a layer containing an oxide of tungsten can be formed at theinterface between the tungsten layer and the insulating layer.Alternatively, a surface of the layer containing tungsten may besubjected to thermal oxidation treatment, oxygen plasma treatment,treatment with a highly oxidizing solution such as ozone water, or thelike, so that a layer containing an oxide of tungsten can be formed. Theplasma treatment and the thermal treatment may be performed in anatmosphere of oxygen, nitrogen, or dinitrogen monoxide alone, or a mixedgas of any of these gasses and another gas. A layer containing anitride, oxynitride, or nitride oxide of tungsten may be formed in amanner similar to that used for forming the layer containing an oxide oftungsten: after a layer containing tungsten is formed, a silicon nitridelayer, a silicon oxynitride layer, or a silicon nitride oxide layer isformed thereover.

Note that the element layer can be transferred to another substrate withany of the following methods: a method in which a separation layer isformed between a substrate and an element layer, and a metal oxide filmis formed between the separation layer and the element layer and thenweakened by crystallization, so that the element layer is separated; amethod in which an amorphous silicon film containing hydrogen is formedbetween a high heat-resistant substrate and an element layer and thenremoved by laser irradiation or etching, so that the element layer isseparated; a method in which a separation layer is formed between asubstrate and an element layer, a metal oxide film is formed between theseparation layer and the element layer, and after the metal oxide filmis weakened by crystallization and part of the separation layer isetched away using a solution or a halogen fluoride gas such as NF₃,BrF₃, or ClF₃, the element layer is separated at the weakened metaloxide film; and a method in which a substrate over which an elementlayer is formed is mechanically removed or etched away using a solutionor a halogen fluoride gas such as NF₃, BrF₃, or ClF₃. It is alsopossible to use a method in which a film containing nitrogen, oxygen,hydrogen, or the like (e.g., an amorphous silicon film containinghydrogen, an alloy film containing hydrogen, or an alloy film containingoxygen) is formed as a separation layer, and the separation layer isirradiated with laser light so that nitrogen, oxygen, hydrogen, or thelike contained in the separation layer is released as gas to promoteseparation between the element layer and the substrate.

A combination of the above separation methods further facilitates thetransferring step. That is, laser irradiation, etching of a separationlayer with a gas or a solution, mechanical removal of a separation layerwith a sharp knife, scalpel, or the like may be performed, so that theelement layer can be easily separated from the substrate, and then, theseparation step can be achieved by physical force (with a machine or thelike).

Alternatively, the interface between the separation layer and theelement layer may be soaked with a liquid (e.g., water), whereby theelement layer is separated from the substrate.

The shape of the light-emitting panel 150 can be freely determined byselecting the shape of the support which serves as a mold and thesupporting member. Accordingly, it is possible to manufacture variouskinds of light-emitting devices capable of being used in a variety ofplaces for a variety of applications, which allows a highly convenientlight-emitting device to be provided.

In addition, the protective film can prevent the element layer and thelight-emitting element from contamination caused by impurities and thuscan increase the reliability of the light-emitting device.

Embodiment 2

In this embodiment, another example of a method for manufacturing alight-emitting device, which is different from that shown in Embodiment1, will be described with reference to FIGS. 2A to 2E. Therefore, thelight-emitting device of this embodiment, except a different part, canbe manufactured in a manner similar to that shown in Embodiment 1; thus,description of the same components or components having the samefunctions as Embodiment 1, and the manufacturing process thereof will beomitted.

FIGS. 2A to 2E are cross-sectional views illustrating a light-emittingdevice and a method for manufacturing the light-emitting device.

In this embodiment, a light-emitting panel is manufactured which is atleast partly curved by processing the shape to be molded after themanufacture of an electrode layer and/or an element layer, and aprotective film covering a surface of the light-emitting panel which isat least partly curved is formed, so that a light-emitting device usingthe light-emitting panel has a more useful function and higherreliability.

The element layer 101 and the light-emitting element 125 electricallyconnected to the element layer 101 are formed over the manufacturingsubstrate 100, and the second sealing member 120 covering the elementlayer 101 and the light-emitting element 125 is formed (see FIG. 2A).The element layer 101 includes a thin film transistor. Next, the elementlayer 101, the light-emitting element 125, and the second sealing member120 are transferred to the third sealing member 128 (see FIG. 2B).

The element layer 101, the light-emitting element 125, the secondsealing member 120, and the third sealing member 128 are provided alongthe curved surface of a curved portion of a support 111 serving as amold for the light-emitting device so that the third sealing member 128is in contact with the support 111 (see FIG. 2C). The third sealingmember 128 may be fixed to the support 111 with an adhesive layer or thelike.

The first sealing member 110 is attached to the exposed element layer101 side to form a curved light-emitting panel 151 (see FIG. 2D).

When the element layer 101, the light-emitting element 125, the secondsealing member 120, the third sealing member 128, and the first sealingmember 110 are shaped, they may be subjected to fixing treatment such asheat treatment or light irradiation treatment so that the obtained shapeis fixed. Alternatively, the element layer 101, the light-emittingelement 125, the second sealing member 120, the third sealing member128, and the first sealing member 110 may be shaped by heat treatmentand cooled while the obtained shape is kept as it is, so that the shapethereof is fixed.

After the light-emitting panel 151 which is curved by shaping is formed,the support 111 is removed from the curved light-emitting panel 151.

The protective film 126 is formed to cover the curved light-emittingpanel 151 in a manner similar to that of Embodiment 1 (see FIG. 2E).Through the above steps, a light-emitting device including the curvedlight-emitting panel 151 can be manufactured.

FIGS. 2A to 2E illustrate an example in which a step of shaping thethird sealing member 128 after the element layer 101, the light-emittingelement 125, and the second sealing member 120 are attached to the thirdsealing member 128 is performed so that the element layer 101, thelight-emitting element 125, and the second sealing member 120 are curvedby the support 111. FIGS. 13A to 13E illustrate an example in which theelement layer 101, the light-emitting element 125, and the secondsealing member 120 are attached to a sealing member which is shaped tobe curved.

The element layer 101 and the light-emitting element 125 electricallyconnected to the element layer 101 is formed over the manufacturingsubstrate 100, and the second sealing member 120 covering the elementlayer 101 and the light-emitting element 125 is formed (see FIG. 13A).Next, the element layer 101, the light-emitting element 125, and thesecond sealing member 120 are transferred to the supporting substrate102 (see FIG. 13B).

The first sealing member 110 is provided along the curved surface of thecurved portion of the support 111 serving as a mold for thelight-emitting device. The first sealing member 110 may be fixed to thesupport 111 with an adhesive layer or the like.

The supporting substrate 102 and the support 111 are arranged so thatthe element layer 101 faces the first sealing member 110, and then, theelement layer 101, the light-emitting element 125, and the secondsealing member 120 are transferred to the first sealing member 110 sidein a direction indicated by arrows so that the element layer 101 is incontact with the first sealing member 110 (see FIG. 13C).

The third sealing member 128 is attached to the exposed second sealingmember 120 side to form a curved light-emitting panel 152 (see FIG.13D).

The protective film 126 is formed to cover the curved light-emittingpanel 152 (see FIG. 13E). Through the above steps, a light-emittingdevice including the curved light-emitting panel 152 can bemanufactured.

In manufactured light-emitting panels, the direction of curves which isdetermined by the order of performing a shaping step to shape thelight-emitting panel can differ like the light-emitting panel 151 andthe light-emitting panel 152. In addition, a light-emitting panel whichreflects the shape of the support 111 can be manufactured by selectingthe shape of the support 111.

The shape of the light-emitting panel can be freely determined byselecting the shape of the support which serves as a mold and thesupporting member. Accordingly, it is possible to manufacture variouskinds of light-emitting devices capable of being used in a variety ofplaces for a variety of applications, which allows a highly convenientlight-emitting device to be provided.

In addition, the protective film can prevent the element layer and thelight-emitting element from contamination caused by impurities and thuscan increase the reliability of the light-emitting device.

Embodiment 3

In this embodiment, an example of a light-emitting device in Embodiment1 or Embodiment 2, which uses a supporting member, will be describedwith reference to FIGS. 3A to 3C and FIGS. 4A to 4C. Therefore, thelight-emitting device of this embodiment, except a different part, canbe manufactured in a manner similar to that shown in Embodiment 1 orEmbodiment 2; thus, description of the same components or componentshaving the same functions as Embodiment 1 or Embodiment 2, and themanufacturing process thereof will be omitted.

FIGS. 3A to 3C and FIGS. 4A to 4C illustrate the light-emitting deviceof this embodiment.

In a manufacturing process of a light-emitting device in thisembodiment, the shape of a light-emitting panel is processed to bemolded after the manufacture of an electrode layer and/or an elementlayer, so that a light-emitting device using the light-emitting panelhas a more useful function. Furthermore, the provision of a protectivefilm increases the reliability of the light-emitting device. Note thatin this embodiment, a supporting member is used to maintain the shape ofthe light-emitting device whose shape is at least partly curved.

In an example of the light-emitting device illustrated in FIGS. 3A to3C, the shape of the curved light-emitting panel 150 in which theelement layer 101 and the light-emitting element 125 are sealed betweenthe first sealing member 110 and the second sealing member 120 and whichis covered with the protective film 126 is fixed (maintained) byattachment of a supporting member to the light-emitting panel 150. Notethat light in the light-emitting panel 150 passes through the firstsealing member 110 and is emitted to a viewer side.

In FIG. 3A, a supporting member 129 a is provided for the light-emittingpanel 150 so as to be in contact with the protective film 126 outsidethe curved portion (on the first sealing member 110 side). In FIG. 3B, asupporting member 129 b is provided for the light-emitting panel 150 soas to be in contact with the protective film 126 inside the curvedportion (on the second sealing member 120 side). In FIG. 3C, asupporting member 129 c is provided for the light-emitting panel 150 incontact with the protective film 126 so as to fill inside of the curvedportion (on the second sealing member 120 side).

The supporting members 129 a, 129 b, and 129 c may be fixed to theprotective film 126 with an adhesive layer. In addition, in the casewhere the supporting member is provided so as to fill inside of thecurved portion of the light-emitting panel like the supporting member129 c, a light curable resin, a thermosetting resin, or the like whichis used for a sealant may be used to attach the supporting member 129 cto the light-emitting panel 150 so that the shape of the light-emittingpanel 150 is retained.

In the case where the supporting members 129 a, 129 b, and 129 c areprovided on the display side from which light of the light-emittingpanel 150 is extracted, a light-transmitting material is used. Thus, inthe case where light in the light-emitting panel 150 passes through thefirst sealing member 110 and is emitted to a viewer side, alight-transmitting supporting member is used as the supporting member129 a of FIG. 3A, whereas the supporting members 129 b and 129 c ofFIGS. 3B and 3C do not need to have a light-transmitting property, andwhen a reflective material is used, efficiency in extracting light fromthe light-emitting panel 150 is effectively improved. With a structureof the light-emitting panel 150, in which light is extracted from boththe first sealing member 110 and the second sealing member 120, thesupporting members 129 a, 129 b, and 129 c need to have alight-transmitting property.

Although examples in each of which the supporting member is provided forthe light-emitting panel 150 covered with the protective film 126 areillustrated in FIGS. 3A to 3C, the protective film may be formed so asto cover the surfaces of the light-emitting panel and the supportingmember after the supporting member is provided for the light-emittingpanel as illustrated in FIGS. 4A to 4C.

The shape of the light-emitting panel 150 can be freely determined byselecting the shape of the support which serves as a mold and thesupporting member. Accordingly, it is possible to manufacture variouskinds of light-emitting devices capable of being used in a variety ofplaces for a variety of applications, which allows a highly convenientlight-emitting device to be provided.

In addition, the protective film can prevent the element layer and thelight-emitting element from contamination caused by impurities and thuscan increase the reliability of the light-emitting device.

Embodiment 4

In this embodiment, an example in which a plurality of element layersfor the light-emitting devices shown in Embodiments 1 to 3 aremanufactured over a large substrate (a so-called multi-panel technology)will be described with reference to FIGS. 7A to 7F. Therefore, thelight-emitting device of this embodiment, except a different part, canbe manufactured in a manner similar to that shown in Embodiments 1 to 3;thus, description of the same components or components having the samefunctions as Embodiments 1 to 3, and the manufacturing process thereofwill be omitted.

As described in the above embodiments, the element layer 101 is formedover the manufacturing substrate 100 and then the element layer 101 istransferred from the manufacturing substrate 100 to the supportingsubstrate 102 that is a flexible substrate.

FIGS. 7A to 7F illustrate a method for transferring a plurality ofelement layers from a large manufacturing substrate to a supportingsubstrate and the supporting substrate is divided into a plurality ofsupporting substrates. FIGS. 7B, 7D, and 7F are plan views, and FIGS.7A, 7C, and 7E are cross-sectional views taken along line X-Y of FIGS.7B, 7D, and 7F, respectively.

Element layers 101 a, 101 b, and 101 c are formed over a largemanufacturing substrate 180 (see FIGS. 7A and 7B).

A supporting substrate 182 with the same size as the manufacturingsubstrate 180 is arranged so as to face the element layers 101 a, 101 b,and 101 c, and the element layers 101 a, 101 b, and 101 c aretransferred from the manufacturing substrate 180 to the supportingsubstrate 182 in a direction indicated by arrows (see FIGS. 7C and 7D).

The supporting substrate 182 is divided into a supporting substrate 102a, a supporting substrate 102 b, and a supporting substrate 102 c forthe element layer 101 a, the element layer 101 b, and the element layer101 c, respectively (see FIGS. 7E and 7F). There is no particularlimitation on a dividing method as long as the supporting substrate canbe cut off physically. For example, the supporting substrate 182 may bedivided with a dicer or a scriber, or by laser irradiation.

The element layers 101 (101 a, 101 b, and 101 c) formed over thesupporting substrates 102 (102 a, 102 b, and 102 c), respectively, forpanels are used for manufacturing light-emitting devices. The subsequentsteps may be performed in a manner similar to those shown in Embodiments1 to 3.

Such a step of simultaneously transferring a plurality of element layerswith the use of a large substrate allows a plurality of light-emittingdevices to be provided at a higher productivity.

Embodiment 5

The invention disclosed in this specification can be applied to apassive matrix light-emitting device as well as an active matrixlight-emitting device.

Thin film transistors are manufactured and used for a pixel portion andfurther a driver circuit, so that a light-emitting device having adisplay function can be manufactured. In addition, when part or whole ofthe driver circuit is formed over the same substrate as the pixelportion with the use of the thin film transistors, a system-on-panel canbe obtained.

The light-emitting device includes a light-emitting element (alsoreferred to as an EL element) as a display element.

Furthermore, the light-emitting device includes a panel in which thedisplay element is sealed, and a module in which an IC or the likeincluding a controller is mounted on the panel. In this embodiment,light-emitting device modules will be illustrated in FIGS. 6A and 6B,FIG. 8, and FIGS. 14A to 14C.

Note that a light-emitting device in this specification refers to animage display device, a display device, or a light source (including alighting device). Furthermore, the light-emitting device also includesthe following modules in its category: a module to which a connectorsuch as a flexible printed circuit (FPC), a tape automated bonding (TAB)tape, or a tape carrier package (TCP) is attached; a module having a TABtape or a TCP at the tip of which a printed wiring board is provided;and a module in which an integrated circuit (IC) is directly mounted ona display element with a chip on glass (COG) method.

The appearance and cross section of a light-emitting panel (alsoreferred to as a light-emitting display panel) which is one embodimentof the light-emitting device will be described with reference to FIGS.6A and 6B, FIG. 8, and FIGS. 14A to 14C. FIGS. 6A and 6B, FIG. 8, andFIGS. 14A to 14C are examples of a light-emitting module (also referredto as a light-emitting display module) in which an FPC 4018 is attachedto a light-emitting panel 4000. Thin film transistors 4010 and 4011 anda light-emitting element 4513 which are formed over a first sealingmember 4001 are sealed between the first sealing member 4001 and a thirdsealing member 4006 with a sealant 4005. FIGS. 6A and 6B are perspectiveviews of the light-emitting modules, and FIG. 8 is a cross-sectionalview taken along line M-N of FIG. 6A. An element layer and thelight-emitting element are sealed with the first sealing member 4001 andthe third sealing member 4006 so as to be interposed therebetween. Thesurface of the light-emitting panel 4000 is covered with a protectivefilm 4007, and the protective film 4007 has an opening in a regionconnected to the FPC 4018.

The light-emitting module of FIG. 6B illustrates an example in which thelight-emitting panel 4000 is fixed to a light-transmitting supportingmember 4040. The light-emitting panel 4000 is provided in contact withan inner surface of the light-transmitting supporting member 4040.

As illustrated in each of FIGS. 6A and 6B, a pixel portion 4002 whichfunctions as a display area is continuously provided on the sidesurfaces and bottom surface of the light-emitting panel that is curved,so that a first display area can be provided on the bottom surface and asecond display area can be provided on the side surfaces.

FIGS. 14A to 14C are other examples of the light-emitting module, eachof which has a structure in which the protective film 4007 is providedafter the FPC 4018 is mounted on the light-emitting panel 4000. In FIGS.14A to 14C, an element portion 4050 denotes the element layer and thelight-emitting element. FIG. 14A illustrates a structure in which theFPC 4018 which is electrically connected to the first sealing member4001, the element portion 4050, and the third sealing member 4006 ismounted on the light-emitting panel 4000 with an anisotropic conductivefilm 4019 and then the light-emitting panel 4000 and the FPC 4018 areall covered with the protective film 4007.

In FIG. 14B, an adhesive layer 4051 is formed so as to fill a regionwhere the first sealing member 4001 and the third sealing member 4006are not stacked, and a sealing member 4052 is attached to the adhesivelayer 4051. The physical strength of the light-emitting panel 4000 canbe improved by provision of the sealing member 4052. FIG. 14Billustrates a structure in which the light-emitting panel 4000, thesealing member 4052, and the FPC 4018 are all covered with theprotective film 4007.

In FIG. 14C, in a manner similar to that of FIG. 14B, the adhesive layer4051 is formed so as to fill a region where the first sealing member4001 and the third sealing member 4006 are not stacked, and the sealingmember 4052 is attached to the adhesive layer 4051. Further, a resinlayer 4053 which covers the light-emitting panel 4000, the sealingmember 4052, and the FPC 4018 is formed to planarize the surfacesthereof. FIG. 14C illustrates a structure in which the protective film4007 is formed so as to cover the surfaces which are planarized by theresin layer 4053.

The sealant 4005 is provided to surround the pixel portion 4002 and ascan line driver circuit 4004 which are provided over the first sealingmember 4001. The third sealing member 4006 is provided over the pixelportion 4002 and the scan line driver circuit 4004. Therefore, the pixelportion 4002 and the scan line driver circuit 4004 are sealed togetherwith the light-emitting element 4513 by the first sealing member 4001,the sealant 4005, and the third sealing member 4006.

A signal line driver circuit 4003 is formed using a single crystalsemiconductor film or a polycrystalline semiconductor film over asubstrate separately prepared, and is mounted by TAB in a regiondifferent from the region surrounded by the sealant.

Further, a variety of signals and potentials are supplied from the FPC4018 to the signal line driver circuit 4003 that is formed separately,and the scan line driver circuit 4004 or the pixel portion 4002.

In FIG. 8, a connection terminal electrode 4015 is formed using the sameconductive film as a first pixel electrode layer 4030, and a terminalelectrode 4016 is formed using the same conductive film as source anddrain electrode layers of the thin film transistors 4010 and 4011.

The connection terminal electrode 4015 is electrically connected to aterminal included in the FPC 4018 via the anisotropic conductive film4019.

Note that there is no particular limitation on the connection method ofthe driver circuit separately formed, and a COG method, a wire bondingmethod, a TAB method, or the like can be used.

The pixel portion 4002 and the scan line driver circuit 4004 which areprovided over the first sealing member 4001 include a plurality of thinfilm transistors. FIG. 8 illustrates the thin film transistor 4010included in the pixel portion 4002 and the thin film transistor 4011included in the scan line driver circuit 4004, for example. Insulatinglayers 4020 and 4021 are provided over the thin film transistors 4010and 4011. Note that an insulating film 4023 is an insulating film whichfunctions as a base film.

Various kinds of thin film transistors can be applied to the thin filmtransistors 4010 and 4011 without particular limitation. FIG. 8illustrates an example in which inverted-staggered thin film transistorshaving a bottom-gate structure are used as the thin film transistors4010 and 4011. Although the thin film transistors 4010 and 4011 arechannel-etched thin film transistors, they may be channel-protectiveinverted-staggered thin film transistors in which a channel protectivefilm is provided over a semiconductor layer.

Light-emitting elements utilizing electroluminescence are classifiedaccording to whether a light-emitting material is an organic compound oran inorganic compound. In general, the former is referred to as anorganic EL element, and the latter is referred to as an inorganic ELelement.

In an organic EL element, voltage is applied to a light-emittingelement, whereby electrons and holes are separately injected from a pairof electrodes into a layer containing a light-emitting organic compound,and thus current flows. The carriers (electrons and holes) arerecombined, and thus, the light-emitting organic compound is excited.The light-emitting organic compound returns to a ground state from theexcited state, thereby emitting light. By such a mechanism, such alight-emitting element is referred to as a current-excitationlight-emitting element.

The inorganic EL elements are classified according to their elementstructures into a dispersion-type inorganic EL element and a thin-filminorganic EL element. A dispersion-type inorganic EL element has alight-emitting layer where particles of a light-emitting material aredispersed in a binder, and its light emission mechanism isdonor-acceptor recombination type light emission that utilizes a donorlevel and an acceptor level. A thin-film inorganic EL element has astructure in which a light-emitting layer is sandwiched betweendielectric layers, which are further sandwiched between electrodes, andits light emission mechanism is localized type light emission thatutilizes inner-shell electron transition of metal ions. Note thatdescription is made here using an organic EL element as a light-emittingelement.

In order to extract light emission from the light-emitting element, atleast one of a pair of electrodes is transparent. Then, a thin filmtransistor and a light-emitting element are formed over a substrate. Thelight-emitting element can have a top emission structure in which lightemission is extracted through the surface opposite to the substrate; abottom emission structure in which light emission is extracted throughthe surface on the substrate side; or a dual emission structure in whichlight emission is extracted through the surface opposite to thesubstrate and the surface on the substrate side, and a light-emittingelement having any of these emission structures can be applied.

The light emitting element 4513 illustrated in FIG. 8 is electricallyconnected to the thin film transistor 4010 which is provided for thepixel portion 4002. Note that in the structure of the light-emittingelement 4513, the first electrode layer 4030, an electroluminescentlayer (EL layer) 4511, and a second electrode layer 4031 are stacked;however, the structure of the light-emitting element 4513 is not limitedto the structure described in this embodiment. The structure of thelight-emitting element 4513 can be changed as appropriate, depending onthe direction in which light is extracted from the light-emittingelement 4513, for example.

A partition 4510 is formed using an organic resin film, an inorganicinsulating film, or an organic polysiloxane film. It is particularlypreferable that the partition 4510 be formed using a photosensitivematerial to have an opening portion over the first electrode layer 4030so that a sidewall of the opening portion is formed as a tilted surfacewith continuous curvature.

The electroluminescent layer 4511 may be formed using either a singlelayer or a plurality of layers stacked.

In order to prevent entry of oxygen, hydrogen, moisture, carbon dioxide,or the like into the light-emitting element 4513, a protective film maybe formed over the second electrode layer 4031 and the partition 4510.As the protective film, a silicon nitride film, a silicon nitride oxidefilm, a DLC film, or the like can be formed. In addition, a space whichis sealed using the first sealing member 4001, the third sealing member4006, and the sealant 4005 is hermetically sealed with a second sealingmember 4514 which functions as a filling member. In this manner, it ispreferable that the light-emitting element be packaged (sealed) with aprotective film (such as a laminate film or an ultraviolet curable resinfilm) or a cover material with high air-tightness and littledegasification so that the light-emitting element is not exposed to theoutside air.

An ultraviolet curable resin or a thermosetting resin can be used forthe second sealing member 4514. For example, polyvinyl chloride (PVC),acrylic, polyimide, an epoxy resin, a silicone resin, polyvinyl butyral(PVB), or ethylene vinyl acetate (EVA) can be used. Instead of thesecond sealing member 4514, an inert gas such as nitrogen or argon canbe used as the filler. For example, nitrogen is used as the filler.

In addition, if needed, an optical film such as a polarizing plate, acircularly polarizing plate (including an elliptically polarizingplate), a retardation plate (a quarter-wave plate or a half-wave plate),or a color filter may be provided as appropriate on a light-emittingsurface of the light-emitting element. Further, the polarizing plate orthe circularly polarizing plate may be provided with an anti-reflectionfilm. For example, anti-glare treatment by which reflected light can bediffused by projections and depressions on the surface so as to reducethe glare can be performed.

When a material which exhibits monochromatic light is formed andcombined with color filters or color conversion layers, full colordisplay can be performed. Needless to say, display of monochromaticlight can also be performed.

A color conversion layer or a coloring layer which functions as a colorfilter may be attached to the light-emitting panel so as to correspondto each pixel after the light-emitting element is sealed between thesealing members and the light-emitting panel is formed. Alternatively,the sealing may be performed together with the light-emitting elementbetween the sealing members. In the case where a coloring layer isprovided between the sealing members, there is no particular limitationon the stack order of the coloring layer, the element layer, and thelight-emitting element, and the following stack order may be given: thefirst sealing member, the coloring layer, the element layer, thelight-emitting element, and the second sealing member; the first sealingmember, the element layer, the coloring member, the light-emittingelement, and the second sealing member; and the first sealing member,the element layer, the light-emitting element, the coloring layer, andthe second sealing member. The position of the coloring layer may beanywhere as long as the light emitted from the light-emitting elementpasses through it before the light is emitted outside.

Emission wavelength range of the light-emitting layer included in theelectroluminescent layer 4511 may vary by pixels so that color displaycan be performed. Typically, light-emitting layers corresponding to R(Red), G (Green), and B (Blue) are formed. In addition, white lightemission may be combined. Also in this case, color purity can beimproved and a pixel region can be prevented from having a mirrorsurface (reflection) by provision of a filter which transmits light ofthe emission wavelength range on the light-emission side of the pixel.

Note that plastic or the like can be used for the first sealing member4001 and the third sealing member 4006. A plastic substrate may be afiberglass-reinforced plastics (FRP) plate, a polyvinyl fluoride (PVF)film, a polyester film, or an acrylic resin film. Alternatively, a sheetwith a structure in which an aluminum foil is sandwiched between PVFfilms or polyester films can be used. In the case where there is nonecessity of a light-transmitting property, a metal film such asstainless steel may be used.

The insulating layer 4020 functions as a protective film of the thinfilm transistors.

Note that the protective film is provided to prevent entry ofcontaminant impurities such as organic substance, a metal, or moisturefloating in air and is preferably a dense film. The protective film maybe formed with a sputtering method as a single layer or stacked layersof a silicon oxide film, a silicon nitride film, a silicon oxynitridefilm, a silicon nitride oxide film, an aluminum oxide film, an aluminumnitride film, aluminum oxynitride film, and/or an aluminum nitride oxidefilm.

The insulating layer 4021 which functions as a planarizing insulatingfilm can be formed using an organic material having heat resistance,such as polyimide, an acrylic resin, a benzocyclobutene-based resin,polyamide, or an epoxy resin. Other than such organic materials, it isalso possible to use a low-dielectric constant material (a low-kmaterial), a siloxane-based resin, PSG (phosphosilicate glass), BPSG(borophosphosilicate glass), or the like. Note that the insulating layer4021 may be formed by stacking a plurality of insulating films formedusing these materials.

There is no particular limitation on the method for forming theinsulating layer 4020 and the insulating layer 4021, and any of thefollowing methods which depend on a material thereof can be used: asputtering method; a CVD method; an evaporation method; a SOG method;spin coating; dipping; spray coating; a droplet discharging method(e.g., an ink-jet method, screen printing, or offset printing).Alternatively, doctor knife, roll coater, curtain coater, knife coater,or the like can be used for forming the insulating layer 4020 and theinsulating layer 4021. In the case where the insulating layers areformed using a material solution, the semiconductor layer may beannealed (at 200° C. to 400° C.) simultaneously with a baking step. Thebaking step of the insulating layers also serves as the annealing stepof the semiconductor layer, whereby a light-emitting device can bemanufactured efficiently.

Display of the light-emitting panel is performed using light transmittedthrough the light-emitting element. Therefore, the sealing members andthin films such as insulating films and conductive films, which areprovided in a display portion (a light-emitting portion) through whichlight passes, all have light-transmitting properties with respect tolight in a visible wavelength range.

The first electrode layer and the second electrode layer (also referredto as a pixel electrode layer and a counter electrode layer,respectively, for example) for applying voltage to the light-emittingelement may have light-transmitting properties or light-reflectingproperties, and which property is selected may be determined by thedirection in which light is extracted, the place where the electrodelayers are provided, or the pattern structure of the electrode layers.

The first electrode layer 4030 and the second electrode layer 4031 canbe formed using a light-transmitting conductive material such as indiumoxide containing tungsten oxide, indium zinc oxide containing tungstenoxide, indium oxide containing titanium oxide, indium tin oxidecontaining titanium oxide, indium tin oxide (hereinafter referred to asITO), indium zinc oxide, or indium tin oxide to which silicon oxide isadded.

The first electrode layer 4030 and the second electrode layer 4031 canbe formed using one kind or plural kinds selected from metal such astungsten (W), molybdenum (Mo), zirconium (Zr), hafnium (Hf), vanadium(V), niobium (Nb), tantalum (Ta), chromium (Cr), cobalt (Co), nickel(Ni), titanium (Ti), platinum (Pt), aluminum (Al), copper (Cu), orsilver (Ag), or an alloy or a metal nitride thereof.

A conductive composition containing a conductive macromolecule (alsoreferred to as a conductive polymer) can be used to form the firstelectrode layer 4030 and the second electrode layer 4031. As theconductive macromolecule, a so-called π-electron conjugated conductivemacromolecule can be used. For example, it is possible to usepolyaniline or a derivative thereof, polypyrrole or a derivativethereof, polythiophene or a derivative thereof, or a copolymer of two ormore kinds of them.

Since the thin film transistors are easily damaged by static electricityor the like, a protective circuit for protecting the driver circuits ispreferably provided over the same substrate (the sealing member) as agate line or a source line. It is preferable to use a non-linear elementfor the protective circuit.

FIG. 8 illustrates an example in which the signal line driver circuit isformed separately and mounted on the first sealing member 4001; however,this embodiment is not limited to this structure. The scan line drivercircuit may be separately formed and then mounted, or only part of thesignal line driver circuit or part of the scan line driver circuit maybe separately formed and then mounted.

This embodiment can be implemented in an appropriate combination withthe structures described in the other embodiments.

Embodiment 6

There is no particular limitation on the kind of thin film transistorincluded in the light-emitting device disclosed in this specification.Therefore, a variety of structures and semiconductor materials can beused for the thin film transistor.

Examples of the structure of the thin film transistor will be describedwith reference to FIGS. 9A to 9D. FIGS. 9A to 9D illustrate examples ofthe thin film transistor which can be used for the thin film transistor4010 in Embodiment 5, and FIGS. 9A to 9D correspond to FIG. 8.

In FIGS. 9A, 9B, 9C, and 9D, thin film transistors 4010 a, 4010 b, 4010c, and 4010 d are respectively provided. Each of the thin filmtransistors 4010 a, 4010 b, 4010 c, and 4010 d is provided over theinsulating film 4023, which is formed over the first sealing member4001. The insulating layer 4020 and the insulating layer 4021 are formedover each of the thin film transistors 4010 a, 4010 b, 4010 c, and 4010d, and the first electrode layer 4030 which is electrically connected toeach of the thin film transistors 4010 a, 4010 b, 4010 c, and 4010 d isprovided thereover.

The thin film transistor 4010 a is an example of the thin filmtransistor 4010 illustrated in FIG. 8, in which wiring layers 405 a and405 b which function as source and drain electrode layers are in contactwith a semiconductor layer 403 without an n⁺ layer interposedtherebetween.

The thin film transistor 4010 a is an inverted-staggered thin filmtransistor, in which a gate electrode layer 401, a gate insulating layer402, the semiconductor layer 403, and the wiring layers 405 a and 405 bserving as source and drain electrode layers are provided over the firstsealing member 4001 which is a substrate having an insulating surfaceand over the insulating film 4023.

The thin film transistor 4010 b is a bottom-gate thin film transistor,in which the gate electrode layer 401, the gate insulating layer 402,the wiring layers 405 a and 405 b which function as source and drainelectrode layers, n⁺ layers 404 a and 404 b which function as source anddrain regions, and the semiconductor layer 403 are provided over thefirst sealing member 4001 which is a substrate having an insulatingsurface and over the insulating film 4023. In addition, the insulatinglayer 4020 is provided in contact with the semiconductor layer 403 so asto cover the thin film transistor 4010 b.

The n⁺ layers 404 a and 404 b may be provided between the gateinsulating layer 402 and the wiring layers 405 a and 405 b.Alternatively, the n⁺ layers may be provided both between the gateinsulating layer and the wiring layers and between the wiring layers andthe semiconductor layer. The n⁺ layers 404 a and 404 b are semiconductorlayers each having a lower resistance than the semiconductor layer 403.

The gate insulating layer 402 exists in the entire region including thethin film transistor 4010 b, and the gate electrode layer 401 isprovided between the gate insulating layer 402 and the first sealingmember 4001 which is a substrate having an insulating surface. Thewiring layers 405 a and 405 b and the n′ layers 404 a and 404 b areprovided over the gate insulating layer 402. Then, the semiconductorlayer 403 is provided over the gate insulating layer 402, the wiringlayers 405 a and 405 b, and the n⁺ layers 404 a and 404 b. Although notillustrated, another wiring layer is provided over the gate insulatinglayer 402 in addition to the wiring layers 405 a and 405 b, and thewiring layer extends beyond the perimeter of the semiconductor layer 403to the outside.

The thin film transistor 4010 c has another structure of the thin filmtransistor 4010 b, in which source and drain electrode layers are incontact with a semiconductor layer without an n⁺ layer interposedtherebetween.

The gate insulating layer 402 exists in the entire region including thethin film transistor 4010 c, and the gate electrode layer 401 isprovided between the gate insulating layer 402 and the first sealingmember 4001 which is a substrate having an insulating surface. Thewiring layers 405 a and 405 b are provided over the gate insulatinglayer 402. Then, the semiconductor layer 403 is provided over the gateinsulating layer 402 and the wiring layers 405 a and 405 b. Although notillustrated, another wiring layer is provided over the gate insulatinglayer 402 in addition to the wiring layers 405 a and 405 b, and thewiring layer extends beyond the perimeter of the semiconductor layer 403to the outside.

The thin film transistor 4010 d is a top-gate thin film transistor andan example of a planar thin film transistor. The semiconductor layer 403including the n⁺ layers 404 a and 404 b which function as source anddrain regions is formed over the first sealing member 4001 which is asubstrate having an insulating surface and over the insulating film4023. The gate insulating layer 402 is formed over the semiconductorlayer 403, and the gate electrode layer 401 is formed over the gateinsulating layer 402. In addition, the wiring layers 405 a and 405 bwhich function as source and drain electrode layers are formed incontact with the n⁺ layers 404 a and 404 b. The n⁺ layers 404 a and 404b are semiconductor regions each having a lower resistance than thesemiconductor layer 403.

The thin film transistor may be a top-gate forward-staggered thin filmtransistor.

Although a single gate structure is described in this embodiment, amulti-gate structure such as a double-gate structure may also be used.In that case, gate electrode layers may be provided above and below thesemiconductor layer, or a plurality of gate electrode layers may beprovided only on one side of (above or below) the semiconductor layer.

There is no particular limitation on the semiconductor material used forthe semiconductor layer. Examples of the material which can be used forthe semiconductor layer of the thin film transistor are described below.

As a material for the semiconductor layer included in the semiconductorelement, it is possible to use an amorphous semiconductor (hereinafteralso referred to as an AS) which is formed with a vapor-phase growthmethod using a semiconductor material gas typified by silane or germaneor with a sputtering method; a polycrystalline semiconductor (acrystalline semiconductor) that is obtained by crystallizing theamorphous semiconductor by utilizing light energy or thermal energy; amicrocrystalline semiconductor (also referred to as a semi-amorphous ormicrocrystal semiconductor, and hereinafter also referred to as an SAS),or the like. The semiconductor layer can be deposited with a sputteringmethod, an LPCVD method, a plasma CVD method, or the like.

In consideration of Gibbs free energy, the microcrystallinesemiconductor film is in a metastable state that is intermediate betweenan amorphous state and a single crystal state. That is, themicrocrystalline semiconductor is in a third state that is stable infree energy, and has short-range order and lattice distortion. Columnaror needle-like crystals grow in the direction of the normal to thesurface of the substrate (the sealing member). The Raman spectrum ofmicrocrystalline silicon which is a typical example of amicrocrystalline semiconductor is shifted to a lower wavenumber sidethan 520 cm⁻¹ that represents single crystal silicon. In other words,the Raman spectrum of microcrystalline silicon has a peak between 520cm⁻¹ that represents single crystal silicon and 480 cm⁻¹ that representsamorphous silicon. Furthermore, the microcrystalline semiconductor filmcontains at least 1 atomic % or more of hydrogen or halogen to terminatedangling bonds. The microcrystalline semiconductor film may furthercontain a rare gas element such as helium, argon, krypton, or neon topromote lattice distortion further, whereby a favorable microcrystallinesemiconductor film with improved stability can be obtained.

This microcrystalline semiconductor film can be formed with ahigh-frequency plasma CVD method with a frequency of several tens ofmegahertz to several hundreds of megahertz, or a microwave plasma CVDapparatus with a frequency of 1 GHz or more. Typically, themicrocrystalline semiconductor film can be formed using silicon hydridesuch as SiH₄, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, or SiF₄, which is dilutedwith hydrogen. Furthermore, the microcrystalline semiconductor film canbe formed with a dilution of one or more kinds of rare gas elementsselected from helium, argon, krypton, or neon, in addition to a dilutionof silicon hydride and hydrogen. In such a case, the flow rate ratio ofhydrogen to silicon hydride is set to 5:1 to 200:1, preferably 50:1 to150:1, and more preferably 100:1.

The amorphous semiconductor is typified by hydrogenated amorphoussilicon, and the polycrystalline semiconductor is typified bypolysilicon or the like. Polysilicon (polycrystalline silicon) includesso-called high-temperature polysilicon that contains polysilicon formedat a process temperature of 800° C. or higher as its main component,so-called low-temperature polysilicon that contains polysilicon formedat a process temperature of 600° C. or lower as its main component, andpolysilicon formed by crystallizing amorphous silicon, using an elementthat promotes crystallization, for example. It is needless to say that amicrocrystalline semiconductor or a semiconductor partly including acrystalline phase can also be used as described above.

As a semiconductor material, a compound semiconductor such as GaAs, InP,SiC, ZnSe, GaN, or SiGe as well as silicon (Si) or germanium (Ge) alonecan be used.

In the case of using a crystalline semiconductor film for thesemiconductor layer, the crystalline semiconductor film may bemanufactured by various methods (e.g., a laser crystallization method, athermal crystallization method, or a thermal crystallization methodusing an element such as nickel that promotes crystallization).Alternatively, a microcrystalline semiconductor which is an SAS can becrystallized by laser irradiation to increase crystallinity. In the casewhere an element that promotes crystallization is not introduced, beforebeing irradiated with laser light, an amorphous silicon film is heatedat 500° C. for one hour in a nitrogen atmosphere, whereby hydrogencontained in the amorphous silicon film is released to a concentrationof 1×10²⁰ atoms/cm³ or less. This is because, if the amorphous siliconfilm contains much hydrogen, the amorphous silicon film is broken bylaser irradiation.

There is no particular limitation on a method for introducing a metalelement into the amorphous semiconductor film as long as the metalelement can exist on the surface of or inside the amorphoussemiconductor film. For example, a sputtering method, a CVD method, aplasma processing method (including a plasma CVD method), an adsorptionmethod, or a coating method using a metal salt solution can be employed.Among them, the method using a solution is simple and easy, and isuseful in terms of easy concentration adjustment of the metal element.At this time, an oxide film is preferably deposited by UV lightirradiation in an oxygen atmosphere, a thermal oxidation method,treatment with ozone water or hydrogen peroxide including a hydroxylradical, or the like in order to improve the wettability of the surfaceof the amorphous semiconductor film and to spread an aqueous solution onthe entire surface of the amorphous semiconductor film.

In a crystallization step for crystallizing the amorphous semiconductorfilm to form a crystalline semiconductor film, an element that promotescrystallization (also referred to as a catalytic element or a metalelement) may be added to the amorphous semiconductor film, andcrystallization may be performed by heat treatment (at 550° C. to 750°C. for 3 minutes to 24 hours). As the element that promotescrystallization, it is possible to use one or more kinds of elementsselected from iron (Fe), nickel (Ni), cobalt (Co), ruthenium (Ru),rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt),copper (Cu), or gold (Au).

In order to remove or reduce the element that promotes crystallizationfrom the crystalline semiconductor film, a semiconductor film containingan impurity element is formed in contact with the crystallinesemiconductor film so as to function as a gettering sink. As theimpurity element, an impurity element imparting n-type conductivity, animpurity element imparting p-type conductivity, a rare gas element, orthe like can be used. For example, it is possible to use one or morekinds of elements selected from phosphorus (P), nitrogen (N), arsenic(As), antimony (Sb), bismuth (Bi), boron (B), helium (He), neon (Ne),argon (Ar), krypton (Kr), or xenon (Xe). A semiconductor film containinga rare gas element is formed over the crystalline semiconductor filmcontaining the element that promotes crystallization, and then heattreatment is performed (at 550° C. to 750° C. for 3 minutes to 24hours). The element that promotes crystallization which is contained inthe crystalline semiconductor film moves into the semiconductor filmcontaining a rare gas element, and thus the element that promotescrystallization which is contained in the crystalline semiconductor filmis removed or reduced. After that, the semiconductor film containing arare gas element which has functioned as a gettering sink is removed.

The amorphous semiconductor film may be crystallized by combiningthermal treatment and laser irradiation. Alternatively, either thermaltreatment or laser irradiation may be performed plural times.

A crystalline semiconductor film can also be formed directly on thesealing member with a plasma method. Alternatively, a crystallinesemiconductor film may be selectively formed over the sealing memberwith a plasma method.

It is also possible to use an oxide semiconductor such as zinc oxide(ZnO) or tin oxide (SnO₂) for the semiconductor layer. In the case ofusing ZnO for the semiconductor layer, a gate insulating layer can beformed using Y₂O₃, Al₂O₃, TiO₂, a stack thereof, or the like, and thegate electrode layer, the source electrode layer, and the drainelectrode layer can be formed using ITO, Au, Ti, or the like. Inaddition, In, Ga, or the like can be added to ZnO.

As the oxide semiconductor, a thin film represented by InMO₃(ZnO), (m>0)can be used. Note that M denotes one or more of metal elements selectedfrom gallium (Ga), iron (Fe), nickel (Ni), manganese (Mn), or cobalt(Co). For example, M is gallium (Ga) in some cases, and in other cases,M contains other metal elements in addition to Ga, such as Ga and Ni orGa and Fe. Furthermore, the above oxide semiconductor may contain atransition metal element such as Fe or Ni or an oxide of the transitionmetal as an impurity element, in addition to a metal element containedas M. For example, an In—Ga—Zn—O-based non-single-crystal film can beused as the oxide semiconductor layer.

As the oxide semiconductor layer (the InMO₃(ZnO), (m>0) film), anInMO₃(ZnO), film (m>0) in which M is another metal element may be usedinstead of the In—Ga—Zn—O-based non-single-crystal film. As the oxidesemiconductor which is applied to the oxide semiconductor layer, any ofthe following oxide semiconductors can be applied in addition to theabove: an In—Sn—Zn—O-based oxide semiconductor; an In—Al—Zn—O-basedoxide semiconductor; a Sn—Ga—Zn—O-based oxide semiconductor; anAl—Ga—Zn—O-based oxide semiconductor; a Sn—Al—Zn—O-based oxidesemiconductor; an In—Zn—O-based oxide semiconductor; a Sn—Zn—O-basedoxide semiconductor; an Al—Zn—O-based oxide semiconductor; an In—O-basedoxide semiconductor; a Sn—O-based oxide semiconductor; and a Zn—O-basedoxide semiconductor.

This embodiment can be implemented in an appropriate combination withthe structures described in the other embodiments.

Embodiment 7

In this embodiment, an example of an element structure of thelight-emitting element used for the light-emitting device which is oneembodiment of the present invention will be described.

In an element structure illustrated in FIG. 12A, an EL layer 1003including a light-emitting region is sandwiched between a pair ofelectrodes (an anode 1001 and a cathode 1002).

The EL layer 1003 includes at least a light-emitting layer 1013, and mayhave a stacked structure including a functional layer in addition to thelight-emitting layer 1013. The functional layer other than thelight-emitting layer 1013 can be formed using one or more of a layercontaining a substance having a high hole-injection property, a layercontaining a substance having a high hole-transport property, a layercontaining a substance having a high electron-transport property, alayer containing a substance having a high electron-injection property,a layer containing a bipolar substance (a substance having a highelectron-transport property and a high hole-transport property), or thelike. Specifically, functional layers such as a hole-injection layer1011, a hole-transport layer 1012, a light-emitting layer 1013, anelectron-transport layer 1014, or an electron-injection layer 1015 canbe used in combination as appropriate.

Next, materials which can be used for the above-described light-emittingelement are specifically described.

The anode 1001 is preferably formed using a metal, an alloy, aconductive compound, a mixture thereof, or the like that has a high workfunction (specifically, a work function of 4.0 eV or higher).Specifically, it is possible to use, for example, indium oxide-tin oxide(ITO: indium tin oxide), indium oxide-tin oxide containing silicon orsilicon oxide, indium oxide-zinc oxide (IZO: indium zinc oxide), orindium oxide containing tungsten oxide and zinc oxide.

These conductive metal oxide films are generally deposited withsputtering, but may also be formed with a sol-gel method or the like.For example, a film of indium oxide-zinc oxide (IZO) can be formed witha sputtering method using a target in which 1 wt % to 20 wt % of zincoxide is added to indium oxide. Further, a film of indium oxidecontaining tungsten oxide and zinc oxide can be formed with a sputteringmethod using a target in which 0.5 wt % to 5 wt % of tungsten oxide and0.1 wt % to 1 wt % of zinc oxide are added to indium oxide.

Besides, it is also possible to use gold (Au), platinum (Pt), nickel(Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt(Co), copper (Cu), palladium (Pd), titanium (Ti), nitride of a metalmaterial (such as titanium nitride), molybdenum oxide, vanadium oxide,ruthenium oxide, tungsten oxide, manganese oxide, titanium oxide, or thelike.

The cathode 1002 can be formed using a metal, an alloy, a conductivecompound, a mixture thereof, or the like that has a low work function(specifically, a work function of 3.8 eV or lower). Specific examples ofthe material for the cathode include an element belonging to Group 1 andan element belonging to Group 2 of the periodic table, i.e., an alkalimetal such as lithium (Li) or cesium (Cs), an alkaline earth metal suchas magnesium (Mg), calcium (Ca), or strontium (Sr), and an alloycontaining these elements (e.g., MgAg or AlLi); and a rare earth metalsuch as europium (Eu) or ytterbium (Yb), and an alloy thereof. A film ofan alkali metal, an alkaline earth metal, or an alloy containing such ametal can be formed with a vacuum evaporation method. An alloy filmcontaining an alkali metal or an alkaline earth metal can also be formedwith a sputtering method. Alternatively, silver paste or the like can beformed with an ink-jet method or the like.

Alternatively, the cathode 1002 can be formed by stacking a film of ametal such as aluminum and a thin film of an alkali metal compound, analkaline earth metal compound, or a rare earth metal compound (e.g.,lithium fluoride (LiF), lithium oxide (LiO_(x)), cesium fluoride (CsF),calcium fluoride (CaF₂), or erbium fluoride (ErF₃)).

In the light-emitting element shown in this embodiment, at least one ofthe anode 1001 and the cathode 1002 may have a light-transmittingproperty.

Next, specific examples of the material used for each layer of the ELlayer 1003 is described below.

The hole-injection layer 1011 is a layer containing a substance having ahigh hole-injection property. As the substance having a highhole-injection property, for example, molybdenum oxide, vanadium oxide,ruthenium oxide, tungsten oxide, or manganese oxide can be used.Alternatively, the hole-injection layer 1011 can be formed using aphthalocyanine-based compound such as phthalocyanine (abbreviation:H₂Pc) or copper phthalocyanine (abbreviation: CuPc); an aromatic aminecompound such as4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB) orN,N′-bis[4-[bis(3-methylphenyl)amino]phenyl]-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: DNTPD); a high molecular compound such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS);or the like. Further alternatively, the hole-injection layer 1011 can beformed using a tris(p-enamine-substituted-aminophenyl)amine compound, a2,7-diamino-9-fluorenylidene compound, atri(p-N-enamine-substituted-aminophenyl)benzene compound, a pyrenecompound having one or two ethenyl groups having at least one arylgroup, N,N′-di(biphenyl-4-yl)-N,N′-diphenylbiphenyl-4,4′-diamine,N,N,N′,N′-tetra(biphenyl-4-yl)biphenyl-4,4′-diamine,N,N,N′,N′-tetra(biphenyl-4-yl)-3,3′-diethylbiphenyl-4,4′-diamine,2,2′-(methylenedi-4,1-phenylene)bis[4,5-bis(4-methoxyphenyl)-2H-1,2,3-triazole],2,2′-(biphenyl-4,4′-diyl)bis(4,5-diphenyl-2H-1,2,3-triazole),2,2′-(3,3′-dimethylbiphenyl-4,4′-diyl)bis(4,5-diphenyl-2H-1,2,3-triazole),bis[4-(4,5-diphenyl-2H-1,2,3-triazol-2-yl)phenyl](methyl)amine, or thelike.

The hole-injection layer 1011 can also be formed using a hole-injectioncomposite material including an organic compound and an inorganiccompound (preferably, an inorganic compound having an electron-acceptingproperty to an organic compound). In the hole-injection compositematerial, electrons are transferred between the organic compound and theinorganic compound and the carrier density is increased; thus, thehole-injection composite material has excellent hole-injection andhole-transport properties.

In the case where the hole-injection layer 1011 is formed using ahole-injection composite material, the hole-injection layer 1011 canform an ohmic contact with the anode 1001; thus, the material of theanode 1001 can be selected regardless of the work function.

The inorganic compound used for the hole-injection composite material ispreferably an oxide of a transition metal. Further, an oxide of metalsbelonging to Group 4 to Group 8 of the periodic table can also be used.Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromiumoxide, molybdenum oxide, tungsten oxide, manganese oxide, and rheniumoxide are preferably used because of their high electron-acceptingproperties. Among them, molybdenum oxide is especially preferablebecause it is stable in the air and has a low hygroscopic property,thereby being easily handled.

As the organic compound used for the hole-injection composite material,it is possible to use various compounds such as an aromatic aminecompound, a carbazole derivative, an aromatic hydrocarbon, and a highmolecular compound (an oligomer, a dendrimer, a polymer, or the like).Note that the organic compound used for the hole-injection compositematerial is preferably an organic compound having a high hole-transportproperty. Specifically, it is preferable to use a substance having ahole mobility of 10⁻⁶ cm²/Vs or higher, though other substances may alsobe used as long as the hole-transport properties thereof are higher thanthe electron-transport properties thereof. The organic compounds whichcan be used for the hole-injection composite material are specificallydescribed below.

Examples of the aromatic amine compound include the following:N,N′-di(p-tolyl)-N,N′-diphenyl-p-phenylenediamine (abbreviation:DTDPPA); 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl(abbreviation: DPAB);N,N′-bis[4-[bis(3-methylphenyl)amino]phenyl]-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: DNTPD); and1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B).

Specific examples of the carbazole derivative which can be used for thehole-injection composite material include the following:3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1);3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2); and3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)-amino]-9-phenylcarbazole(abbreviation: PCzPCN1).

Further, as the carbazole derivative, it is also possible to use thefollowing: 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP);1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB);9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation: CzPA);1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene; or the like.

Examples of the aromatic hydrocarbon which can be used for thehole-injection composite material include the following:2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA);2-tert-butyl-9,10-di(1-naphthyl)anthracene;9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA);2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA);9,10-di(2-naphthyl)anthracene (abbreviation: DNA);9,10-diphenylanthracene (abbreviation: DPAnth); 2-tert-butylanthracene(abbreviation: t-BuAnth); 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA);2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene;9,10-bis[2-(1-naphthyl)phenyl]anthracene;2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene;2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene; 9,9′-bianthryl;10,10′-diphenyl-9,9′-bianthryl;10,10′-bis(2-phenylphenyl)-9,9′-bianthryl;10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl; anthracene;tetracene; rubrene; perylene; and 2,5,8,11-tetra(tert-butyl)perylene.Besides, pentacene, coronene, or the like can also be used. Further, itis more preferable to use an aromatic hydrocarbon that has a holemobility of 1×10⁻⁶ cm²/Vs or higher and has 14 to 42 carbon atoms.

The aromatic hydrocarbon which can be used for the hole-injectioncomposite material may have a vinyl skeleton. Examples of the aromatichydrocarbon having a vinyl skeleton include4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

Examples of the high molecular compound which can be used for thehole-injection composite material include poly(N-vinylcarbazole)(abbreviation: PVK) and poly(4-vinyltriphenylamine) (abbreviation:PVTPA).

The hole-transport layer 1012 is a layer containing a substance having ahigh hole-transport property. The substance having a high hole-transportproperty is preferably an aromatic amine compound (i.e., a compoundhaving a benzene ring-nitrogen bond), for example. Widely used examplesof the material are as follows:4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl; a derivative thereofsuch as 4,4′-bis[N-(1-napthyl)-N-phenylamino]biphenyl (hereinafterreferred to as NPB); and a starburst aromatic amine compound such as4,4′,4″-tris(N,N-diphenyl-amino)triphenylamine or4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine. Thesesubstances are mainly substances having a hole mobility of 10⁻⁶ cm²/Vsor higher, though other substances may also be used as long as thehole-transport properties thereof are higher than the electron-transportproperties thereof. Note that the hole-transport layer 1012 is notlimited to a single layer, but may be a mixed layer of theabove-described substances, or stacked layers of two or more layerscontaining the above-described substances.

Alternatively, a hole-transport material may be added to a highmolecular compound such as PMMA, which is electrically inactive.

Further alternatively, a high molecular compound such aspoly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine)(abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylaide](abbreviation: PTPDMA), orpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD) may be used. Furthermore, the above-described hole-transportmaterial may be added to those high molecular compounds as appropriate.Further, the hole-transport layer 1012 can also be formed using atris(p-enamine-substituted-aminophenyl)amine compound, a2,7-diamino-9-fluorenylidene compound, atri(p-N-enamine-substituted-aminophenyl)benzene compound, a pyrenecompound having one or two ethenyl groups having at least one arylgroup, N,N′-di(biphenyl-4-yl)-N,N′-diphenylbiphenyl-4,4′-diamine,N,N,N′,N′-tetra(biphenyl-4-yl)biphenyl-4,4′-diamine,N,N,N′,N′-tetra(biphenyl-4-yl)-3,3′-diethylbiphenyl-4,4′-diamine,2,2′-(methylenedi-4,1-phenylene)bis[4,5-bis(4-methoxyphenyl)-2H-1,2,3-triazole],2,2′-(biphenyl-4,4′-diyl)bis(4,5-diphenyl-2H-1,2,3-triazole),2,2′-(3,3′-dimethylbiphenyl-4,4′-diyl)bis(4,5-diphenyl-2H-1,2,3-triazole),bis[4-(4,5-diphenyl-2H-1,2,3-triazol-2-yl)phenyl](methyl)amine, or thelike.

The light-emitting layer 1013 is a layer containing a light-emittingsubstance, and can be formed using a wide variety of materials. Forexample, a fluorescent compound that exhibits fluorescence or aphosphorescent compound that exhibits phosphorescence can be used as thelight-emitting substance. Organic compound materials which can be usedfor the light-emitting layer is shown below, though the materials whichcan be used for the light-emitting element are not limited to thefollowing examples.

Blue to blue-green light emission can be obtained, for example, usingperylene, 2,5,8,11-tetra-t-butylperylene (abbreviation: TBP),9,10-diphenylanthracene, or the like as a guest material, and dispersingthe guest material in a suitable host material. Blue to blue-green lightemission can also be obtained from a styrylarylene derivative such as4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) or ananthracene derivative such as 9,10-di-2-naphthylanthracene(abbreviation: DNA) or 9,10-bis(2-naphthyl)-2-t-butylanthracene(abbreviation: t-BuDNA). Alternatively, a polymer such aspoly(9,9-dioctylfluorene) may be used. As a guest material for bluelight emission, a styrylamine derivative is preferably used, andexamples thereof includeN,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S) andN,N′-diphenyl-N,N′-bis(9-phenyl-9H-carbazol-3-yl)stilbene-4,4′-diamine(abbreviation: PCA2S). Among them, YGA2S is preferably used because ithas a peak at around 450 nm. As a host material, an anthracenederivative such as 9,10-bis(2-naphthyl)-2-t-butylanthracene(abbreviation: t-BuDNA) or9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA) ispreferably used. Among them, CzPA is preferably used because it iselectrochemically stable.

Blue-green to green light emission can be obtained, for example, using acoumarin dye such as coumarin 30 or coumarin 6;bis[2-(2,4-difluorophenyl)pyridinato]picolinatoiridium (abbreviation:FIrpic); bis(2-phenylpyridinato)acetylacetonatoiridium (abbreviation:Ir(ppy)₂(acac)); or the like as a guest material and dispersing theguest material in a suitable host material. Blue-green to green lightemission can also be obtained by dispersing the above-described peryleneor TBP in a suitable host material at a high concentration of 5 wt % ormore. Alternatively, blue-green to green light emission can be obtainedfrom a metal complex such as BAlq, Zn(BTZ)₂, orbis(2-methyl-8-quinolinolato)chlorogallium (Ga(mq)₂Cl). Furtheralternatively, a polymer such as poly(p-phenylenevinylene) may be used.As a guest material for a blue-green to green light-emitting layer, ananthracene derivative is preferably used because high emissionefficiency can be obtained. For example, blue-green light emission withhigh efficiency can be obtained using9,10-bis{4-[N-(4-diphenylamino)phenyl-N-phenyl]aminophenyl}-2-tert-butylanthracene(abbreviation: DPABPA). Further, an anthracene derivative in which anamino group has been substituted into the 2-position is preferably usedbecause green light emission with high efficiency can be obtained. Inparticular, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA) that has a long life is preferably used. As ahost material for these materials, an anthracene derivative ispreferably used, and the above-described CzPA is preferably used becauseit is electrochemically stable. Further, in the case where alight-emitting element having two peaks in the blue to green wavelengthrange is manufactured combining green light emission and blue lightemission, an anthracene derivative having an electron-transportproperty, such as CzPA, is preferably used as a host material for ablue-light-emitting layer and an aromatic amine compound having ahole-transport property, such as NPB, is preferably used as a hostmaterial for a green-light-emitting layer, so that light emission can beobtained at the interface between the blue-light-emitting layer and thegreen-light-emitting layer. That is, in such a case, an aromatic aminecompound like NPB is preferably used as a host material of agreen-light-emitting material such as 2PCAPA.

Yellow to orange light emission can be obtained, for example, usingrubrene;4-(dicyanomethylene)-2-[p-(dimethylamino)styryl]-6-methyl-4H-pyran(abbreviation: DCM1);4-(dicyanomethylene)-2-methyl-6-(9-julolidyl)ethenyl-4H-pyran(abbreviation: DCM2); bis[2-(2-thienyl)pyridinato]acetylacetonatoiridium(abbreviation: Ir(thp)₂(acac));bis(2-phenylquinolinato)acetylacetonatoiridium (abbreviation:Ir(pq)₂(acac)); or the like as a guest material and dispersing the guestmaterial in a suitable host material. In particular, a tetracenederivative such as rubrene is preferably used as a guest materialbecause it is highly efficient and chemically stable. As a host materialin that case, an aromatic amine compound such as NPB is preferably used.Alternatively, a metal complex such as bis(8-quinolinolato)zinc(abbreviation: Znq₂) or bis[2-cinnamoyl-8-quinolinolato]zinc(abbreviation: Znsq₂) can be used as a host material. Furtheralternatively, a polymer such aspoly(2,5-dialkoxy-1,4-phenylenevinylene) may be used.

Orange to red light emission can be obtained, for example, using4-(dicyanomethylene)-2,6-bis[p-(dimethylamino)styryl]-4H-pyran(abbreviation: BisDCM);4-(dicyanomethylene)-2,6-bis[2-(julolidin-9-yl)ethynyl]-4H-pyran(abbreviation: DCM1);4-(dicyanomethylene)-2-methyl-6-(9-julolidyl)ethenyl-4H-pyran(abbreviation: DCM2); bis[2-(2-thienyl)pyridinato]acetylacetonatoiridium(abbreviation: Ir(thp)₂(acac)), or the like as a guest material, anddispersing the guest material in a suitable host material. Orange to redlight emission can also be obtained from a metal complex such asbis(8-quinolinolato)zinc (abbreviation: Znq₂) orbis[2-cinnamoyl-8-quinolinolato]zinc (abbreviation: Znsq₂).Alternatively, a polymer such as poly(3-alkylthiophene) may be used. Asa guest material exhibiting red light emission, it is preferable to usea 4H-pyran derivative that has high emission efficiency, such as4-(dicyanomethylene)-2,6-bis[p-(dimethylamino)styryl]-4H-pyran(abbreviation: BisDCM),4-(dicyanomethylene)-2,6-bis[2-(julolidin-9-yl)ethynyl]-4H-pyran(abbreviation: DCM1),4-(dicyanomethylene)-2-methyl-6-(9-julolidyl)ethenyl-4H-pyran(abbreviation: DCM2),{2-isopropyl-6-[2-(2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTI), or{2,6-bis[2-(2,3,6,7-tetrahydro-8-methoxy-1,1,7,7-tetramethyl-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: BisDCJTM). Among them, DCJTI and BisDCJTM are preferablyused because they have an emission peak at around 620 nm.

Note that the light-emitting layer 1013 may have a structure in whichany of the above light-emitting substances (guest materials) isdispersed in another substance (a host material). A substance having ahigh light-emitting property can be dispersed in various kinds ofsubstances, and it is preferably dispersed in a substance that has alowest unoccupied molecular orbital (LUMO) level higher than that of thesubstance having a high light-emitting property and has a highestoccupied molecular orbital (HOMO) level lower than that of the substancehaving a high light-emitting property.

Specific examples of the substance in which the light-emitting substanceis dispersed are as follows: a metal complex such astris(8-quinolinolato)aluminum(III) (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq),bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), orbis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); aheterocyclic compound such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ),2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), orbathocuproine (abbreviation: BCP); a condensed aromatic compound such as9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA),3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl)anthracene(abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA),2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),9,9′-bianthryl (abbreviation: BANT),9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation: DPNS),9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2),3,3′,3″-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3),9,10-diphenylanthracene (abbreviation: DPAnth), or6,12-dimethoxy-5,11-diphenylchrysene; and an aromatic amine compoundsuch asN,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine(abbreviation: DPhPA),N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA),N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine(abbreviation: PCAPBA),N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA), NPB (or α-NPD), TPD, DFLDPBi, or BSPB.

Further, as the substance into which the light-emitting substance isdispersed, a plurality of kinds of substances can be used. For example,a substance such as rubrene, which suppresses crystallization, may befurther added in order to prevent crystallization. Moreover, NPB, Alq,or the like may be further added in order to increase the efficiency inenergy transfer to the light-emitting substance.

By dispersing a light-emitting substance in another substance,crystallization of the light-emitting layer 1013 can be suppressed.Furthermore, it is also possible to suppress concentration quenching dueto a high concentration of a light-emitting substance.

The electron-transport layer 1014 is a layer containing a substancehaving a high electron-transport property. Examples of the substancehaving a high electron-transport property include a metal complex havinga quinoline skeleton or a benzoquinoline skeleton, such astris(8-quinolinolato)aluminum (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq₂), orbis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation:BAlq). Alternatively, a metal complex having an oxazole-based ligand ora thiazole-based ligand, such asbis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)₂) orbis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)₂),can be used. Besides the metal complexes, it is also possible to use2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen),bathocuproine (abbreviation: BCP),bis[3-(1H-benzimidazol-2-yl)-fluoren-2-olato]zinc(II),bis[3-(1H-benzimidazol-2-yl)-fluoren-2-olato]beryllium(II),bis[2-(1H-benzimidazol-2-yl)dibenzo[b,d]furan-3-olato](phenolato)aluminum(III),bis[2-(benzoxazol-2-yl)-7,8-methylenedioxydibenzo[b,d]furan-3-olato](2-naphtholato)aluminum(III), or the like. The substances described hereare mainly substances having an electron mobility of 10⁻⁶ cm²/Vs orhigher, though the electron-transport layer 1014 may be formed usingother substances as long as the electron-transport properties thereofare higher than the hole-transport properties thereof. Note that theelectron-transport layer 1014 is not limited to a single layer, but maybe stacked layers of two or more layers containing the above-describedsubstances.

The electron-injection layer 1015 is a layer containing a substancehaving a high electron-injection property. Examples of the substancehaving a high electron-injection property include an alkali metal, analkaline earth metal, and a compound of these metals, such as lithiumfluoride (LiF), cesium fluoride (CsF), or calcium fluoride (CaF₂). It isalso possible to use an electron-injection composite material includingan organic compound (preferably, an organic compound having anelectron-transport property) and an inorganic compound (preferably, analkali metal, an alkaline earth metal, a rare earth metal, or a compoundof these metals). As the electron-injection composite material, forexample, a layer formed using Alq mixed with magnesium (Mg) can be used.Such a structure increases the efficiency in electron injection from thecathode 1002.

In the case where the electron-injection layer 1015 is formed using theabove-described electron-injection composite material, a variety ofconductive materials such as Al, Ag, ITO, or ITO containing silicon orsilicon oxide can be used as the material of the cathode 1002 regardlessof the work function.

The EL layer 1003 can be formed stacking the above layers in appropriatecombination. Note that the light-emitting layer 1013 may have a stackedstructure of two or more layers. When the light-emitting layer 1013 hasa stacked structure of two or more layers and the kind of light-emittingsubstance for each light-emitting layer is changed, various emissioncolors can be obtained. In addition, plural kinds of light-emittingsubstances having different emission colors are used, so that lightemission with a broad spectrum or white light emission can also beobtained. A light-emitting layer having a stacked structure ispreferably used particularly for a lighting device that requires highluminance.

As a method for forming the EL layer 1003, various methods (e.g., a dryprocess or a wet process) which depend on a material used can beselected as appropriate. For example, a vacuum evaporation method, asputtering method, an ink-jet method, or a spin coating method can beused. Each layer of the EL layer 1003 may be formed with a differentmethod.

Further, the light-emitting element shown in this embodiment can beformed by various methods regardless of whether it is a dry process(e.g., a vacuum evaporation method or a sputtering method) or a wetprocess (e.g., an ink-jet method or a spin coating method).

The light-emitting element shown in this embodiment may have a structureillustrated in FIG. 12B, a so-called stacked element structure in whicha plurality of the EL layers 1003 are stacked between a pair ofelectrodes. Note that in the case where the El layer 1003 has a stackedstructure including, for example, n layers (n is a natural number of twoor more), an intermediate layer 1004 is provided between an m-th (m is anatural number, 1≤m≤n−1) EL layer and an (m+1)-th EL layer.

The intermediate layer 1004 has a function of, when a voltage is appliedto the anode 1001 and the cathode 1002, injection of electrons to one ofthe EL layers 1003 in contact with the intermediate layer 1004, which ison the anode 1001 side, and injection of holes to the other EL layer1003 on the cathode 1002 side.

The intermediate layer 1004 can be formed using the above-describedcomposite materials (a hole-injection composite material or anelectron-injection composite material) of an organic compound and aninorganic compound, metal oxides, and the like in appropriatecombination. More preferably, the intermediate layer 1004 is formedusing a combination of a hole-injection composite material and othermaterials. Such materials used for the intermediate layer 1004 haveexcellent carrier-injection properties and carrier-transport properties,whereby a light-emitting element driven with low current and low voltagecan be realized.

In the case where an EL layer has two stacked layers in the stackedelement structure, white light emission can be extracted outside byallowing a first EL layer and a second EL layer to emit light ofcomplementary colors. Note that white light emission can also beobtained in a structure in which each of the first EL layer and thesecond EL layer includes a plurality of light-emitting layers emittinglight of complementary colors. Examples of complementary colors includeblue and yellow, and blue-green and red. A substance emitting light ofblue, yellow, blue-green, or red may be selected as appropriate from,for example, the light-emitting substances given above.

The following is an example of the structure in which each of the firstEL layer and the second EL layer includes a plurality of light-emittinglayers emitting light of complementary colors.

For example, the first EL layer includes a first light-emitting layerthat emits light having an emission spectrum with a peak in the blue toblue-green wavelength range, and a second light-emitting layer thatemits light having an emission spectrum with a peak in the yellow toorange wavelength range. The second EL layer includes a thirdlight-emitting layer that emits light having an emission spectrum with apeak in the blue-green to green wavelength range, and a fourthlight-emitting layer that emits light having an emission spectrum with apeak in the orange to red wavelength range.

In this case, light emission from the first EL layer is a combination oflight emission from both the first light-emitting layer and the secondlight-emitting layer and thus exhibits an emission spectrum having peaksboth in the blue to blue-green wavelength range and in the yellow toorange wavelength range. That is, the first EL layer emits light oftwo-wavelength white color or almost white color.

Further, light emission from the second EL layer is a combination oflight emission from both the third light-emitting layer and the fourthlight-emitting layer and thus exhibits an emission spectrum having peaksboth in the blue-green to green wavelength range and in the orange tored wavelength range. That is, the second EL layer emits light oftwo-wavelength white color or almost white color, which is differentfrom that of the first EL layer.

Accordingly, a combination of the light-emission from the first EL layerand the light emission from the second EL layer provides white lightemission that covers the blue to blue-green wavelength range, theblue-green to green wavelength range, the yellow to orange wavelengthrange, and the orange to red wavelength range.

Note that in the above-described stacked element structure, theintermediate layer between the stacked EL layers allows the element tohave a long lifetime in a high-luminance region while the currentdensity is kept low. In addition, the voltage drop due to the resistanceof the electrode material can be reduced, resulting in uniform lightemission in a large area.

This embodiment can be implemented in an appropriate combination withthe structures described in the other embodiments.

Embodiment 8

A light-emitting device disclosed in this specification can be appliedto a variety of electronic appliances (including an amusement machine).Examples of electronic appliances include a television set (alsoreferred to as a television or a television receiver), a monitor of acomputer or the like, a camera such as a digital camera or a digitalvideo camera, a digital photo frame, a cellular phone (also referred toas a mobile phone or a mobile phone set), a portable game console, aportable information terminal, an audio reproducing device, and alarge-sized game machine such as a pachinko machine.

In this embodiment, an example of a cellular phone using thelight-emitting device disclosed in this specification is described withreference to FIGS. 10A to 10D and FIG. 11.

FIG. 10C is a front view of the cellular phone; FIG. 10D, a side view;and FIG. 10B, a top view. The cellular phone includes a housing 1411 aand a housing 1411 b, which include a light-transmitting supportingmember at least in a region to be a display area. FIG. 10A is across-sectional view of the inside of the housing 1411 a and the housing1411 b. The front of the housing 1411 a has a rectangular shape with alonger side and a shorter side, which may have a round corner. In thisembodiment, the direction parallel to the longer side of the rectanglethat is the front shape is referred to as a longitudinal direction, andthe direction parallel to the shorter side thereof is referred to as alateral direction.

The sides of the housing 1411 a and the housing 1411 b also have arectangular shape with a longer side and a shorter side, which may havea round corner. In this embodiment, the direction parallel to the longerside of the rectangle that is the side shape is referred to as alongitudinal direction, and the direction parallel to the shorter sideis referred to as a depth direction.

The cellular phone illustrated in FIGS. 10A to 10D includes a displayarea 1413, operating buttons 1404, and a touch panel 1423, and thehousings 1411 a and 1411 b include a light-emitting panel 1421 and awiring board 1425. The touch panel 1423 may be provided as needed.

As the light-emitting panel 1421, the light-emitting panel and thelight-emitting module described in Embodiments 1 to 7 may be used.

As illustrated in FIGS. 10B and 10C, the light-emitting panel 1421 isarranged along the shape of the housing 1411 a so as to cover not onlythe front area on the viewer side but also part of the top area and thebottom area. Accordingly, a display area 1427 can be formed on the topof the cellular phone in the longitudinal direction to be connected tothe display area 1413. That is, the display area 1427 is provided alsoon the top surface of the cellular phone, which makes it possible to seethe display area 1427 without taking out the cellular phone from, forexample, the breast pocket.

On the display areas 1413 and 1427, incoming mails or calls, dates,phone numbers, personal names, and the like may be displayed. Displaymay be performed only in the display area 1427 and not be performed inthe other regions as needed, resulting in saving of energy.

FIG. 11 is a cross-sectional view of FIG. 10D. As illustrated in FIG.11, the light-emitting panel 1421 is continuously provided on the top,front, and bottom of the inside of the housing 1411 a. A battery 1426and the wiring board 1425 electrically connected to the light-emittingpanel 1421 are provided on the backside of the light-emitting panel1421. Furthermore, the touch panel 1423 is provided on the outside ofthe housing 1411 a (on the viewer side).

Images and letters can be displayed on the cellular phone of thisembodiment, whether it is placed horizontally or vertically for alandscape mode or a portrait mode.

The light-emitting panel 1421 is not manufactured separately in thefront area and the top area, but manufactured to cover both the frontdisplay area 1413 and the top display area 1427, whereby manufacturingcost and time can be reduced.

The touch panel 1423 is provided on the housing 1411 a, and buttons 1414of the touch panel are displayed on the display area 1413. By touchingthe buttons 1414 with a finger or the like, contents displayed on thedisplay area 1413 can be controlled. Furthermore, making calls orcomposing mails can also be performed by touching the buttons 1414 onthe display area 1413 with a finger or the like.

The buttons 1414 of the touch panel 1423 may be displayed when needed,and images or letters can be displayed on the entire display area 1413when the buttons 1414 are not necessary.

Furthermore, the upper longer side in a cross section of the cellularphone may also have a curvature radius. When the cellular phone isformed so that the cross section thereof has a curvature radius in theupper long side, the light-emitting panel 1421 and the touch panel 1423also have a curvature radius in an upper longer side in a cross section.In addition, the housing 1411 a also has a curved shape. In other words,the display area 1413 on the front is curved outwards.

The present application is based on Japanese Patent Application serialNo. 2009-122664 filed with Japan Patent Office on May 21, 2009, theentire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A light-emitting device comprising: alight-emitting panel having a shape at least partly curved; and aprotective film continuously covering an entire surface of thelight-emitting panel so that the light-emitting panel is positionedbetween a first part of the protective film and a second part of theprotective film, wherein the entire surface of the light-emitting panelis covered with only the protective film.
 2. The light-emitting deviceaccording to claim 1, wherein the light-emitting panel further comprisesa first sealing member, an element layer, a light-emitting element, anda second sealing member, wherein the element layer and thelight-emitting element are between the first sealing member and thesecond sealing member.
 3. The light-emitting device according to claim2, wherein the protective film is in contact with the first sealingmember and the second sealing member.
 4. The light-emitting deviceaccording to claim 1, wherein the light-emitting panel comprises anelement layer having a shape at least partly curved.
 5. Thelight-emitting device according to claim 1, wherein the light-emittingpanel comprises a transistor, and wherein the transistor comprises anoxide semiconductor layer in a channel formation region.
 6. Thelight-emitting device according to claim 1, further comprising asupporting member in contact with an outer side surface or an inner sidesurface of the light-emitting panel, wherein the supporting membermaintains the shape of the light-emitting panel.
 7. The light-emittingdevice according to claim 1, further comprising a supporting member incontact with the protective film to cover an outer side surface or aninner side surface of the light-emitting panel, wherein the supportingmember maintains the shape of the light-emitting panel.
 8. Thelight-emitting device according to claim 1, wherein the protective filmcomprises an inorganic material.
 9. The light-emitting device accordingto claim 1, wherein the protective film comprises silicon nitride. 10.The light-emitting device according to claim 1, wherein each of thefirst part of the protective film and the second part of the protectivefilm comprises the same material.
 11. A light-emitting devicecomprising: a light-emitting panel having a shape at least partlycurved; and a protective film continuously covering a side surface, anouter side surface and an inner side surface of the light-emitting panelso that the light-emitting panel is positioned between a first part ofthe protective film and a second part of the protective film, whereinthe outer side surface and the inner side surface of the light-emittingpanel is covered with only the protective film.
 12. The light-emittingdevice according to claim 11, wherein the light-emitting panel furthercomprises a first sealing member, an element layer, a light-emittingelement, and a second sealing member, wherein the element layer and thelight-emitting element are between the first sealing member and thesecond sealing member.
 13. The light-emitting device according to claim12, wherein the protective film is in contact with the first sealingmember and the second sealing member.
 14. The light-emitting deviceaccording to claim 11, wherein the light-emitting panel comprises anelement layer having a shape at least partly curved.
 15. Thelight-emitting device according to claim 11, wherein the light-emittingpanel comprises a transistor, and wherein the transistor comprises anoxide semiconductor layer in a channel formation region.
 16. Thelight-emitting device according to claim 11, further comprising asupporting member in contact with the outer side surface or the innerside surface of the light-emitting panel, wherein the supporting membermaintains the shape of the light-emitting panel.
 17. The light-emittingdevice according to claim 11, further comprising a supporting member incontact with the protective film to cover the outer side surface or theinner side surface of the light-emitting panel, wherein the supportingmember maintains the shape of the light-emitting panel.
 18. Thelight-emitting device according to claim 11, wherein the protective filmcomprises an inorganic material.
 19. The light-emitting device accordingto claim 11, wherein the protective film comprises silicon nitride. 20.The light-emitting device according to claim 11, wherein each of thefirst part of the protective film and the second part of the protectivefilm comprises the same material.
 21. A light-emitting devicecomprising: a light-emitting panel having a shape at least partlycurved: and a protective film continuously encapsulating thelight-emitting panel so that the light-emitting panel is positionedbetween a first part of the protective film and a second part of theprotective film.
 22. The light-emitting device according to claim 21,wherein the light-emitting panel further comprises a first sealingmember, an element layer, a light-emitting element, and a second sealingmember, wherein the element layer and the light-emitting element arebetween the first sealing member and the second sealing member.
 23. Thelight-emitting device according to claim 22, wherein the protective filmis in contact with the first sealing member and the second sealingmember.
 24. The light-emitting device according to claim 21, wherein thelight-emitting panel comprises an element layer having a shape at leastpartly curved.
 25. The light-emitting device according to claim 21,wherein the light-emitting panel comprises a transistor, and wherein thetransistor comprises an oxide semiconductor layer in a channel formationregion.
 26. The light-emitting device according to claim 21, furthercomprising a supporting member in contact with an outer side surface oran inner side surface of the light-emitting panel, wherein thesupporting member maintains the shape of the light-emitting panel. 27.The light-emitting device according to claim 21, further comprising asupporting member in contact with the protective film to cover an outerside surface or an inner side surface of the light-emitting panel,wherein the supporting member maintains the shape of the light-emittingpanel.
 28. The light-emitting device according to claim 21, wherein theprotective film comprises an inorganic material.
 29. The light-emittingdevice according to claim 21, wherein the protective film comprisessilicon nitride.
 30. The light-emitting device according to claim 21,wherein each of the first part of the protective film and the secondpart of the protective film comprises the same material.